bio 111 chapter 9 & 11
3) When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is _____. A) reduced, and energy is released B) reduced, and energy is consumed C) oxidized, and energy is consumed D) oxidized, and energy is released
A) reduced, and energy is released
13) Starting with one molecule of glucose, the energy-containing products of glycolysis are _____. A) 2 NAD+, 2 pyruvate, and 2 ATP B) 2 NADH, 2 pyruvate, and 2 ATP C) 2 FADH2, 2 pyruvate, and 4 ATP D) 6 CO2, 2 pyruvate, and 2 ATP
B) 2 NADH, 2 pyruvate, and 2 ATP
10) A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply? A) He or she has to sit down and rest. B) Catabolic processes are activated that generate more ATP. C) ATP is transported into the cell from the circulatory system. D) Other cells take over, and the muscle cells that have used up their ATP cease to function.
B) Catabolic processes are activated that generate more ATP.
29) In general, a signal transmitted via phosphorylation of a series of proteins _____. A) results in a conformational change to each protein B) requires binding of a hormone to an intracellular receptor C) activates a transcription event D) generates ATP in the process of signal transduction
A) results in a conformational change to each protein
39) Viagra causes dilation of blood vessels and increased blood flow to the penis, facilitating erection. Viagra acts by inhibiting _____. A) the hydrolysis of cGMP to GMP B) the hydrolysis of GTP to GDP C) the dephosphorylation of cGMP D) the removal of GMP from the cell
A) the hydrolysis of cGMP to GMP
48) In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of _____. A) ATP, CO2, and ethanol (ethyl alcohol) B) ATP, CO2, and lactate C) ATP, NADH, and pyruvate D) ATP, pyruvate, and acetyl CoA
A) ATP, CO2, and ethanol (ethyl alcohol)
4) Which of the listed statements describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) O2 is reduced and CO2 is oxidized.
A) C6H12O6 is oxidized and O2 is reduced.
58) In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following, if found in cells or organisms as they age, would provide evidence that this is related to cell signaling? A) Growth factor ligands do not bind as efficiently to receptors. B) Hormone concentrations decrease. C) cAMP levels change very frequently. D) Enzymatic activity declines.
A) Growth factor ligands do not bind as efficiently to receptors.
57) A young dog has never had much energy. He is brought to a veterinarian for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition? A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. B) His cells cannot move NADH from glycolysis into the mitochondria. C) His cells lack the enzyme in glycolysis that forms pyruvate. D) His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
57) In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways? A) It prevents the caspase activity of ced-3 and ced-4. B) Ced-9 remains inactive until it is signaled by ced-3 and other caspases. C) Ced-9 cleaves to produce ced-3 and ced-4. D) Ced-9 prevents blebbing by its action on the cell membrane.
A) It prevents the caspase activity of ced-3 and ced-4.
42) You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave his body? A) It was released as CO2 and H2O. B) It was converted to heat and then released. C) It was converted to ATP, which weighs much less than fat. D) It was converted to urine and eliminated from the body.
A) It was released as CO2 and H2O.
20) If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system? A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. B) It would be able to carry out reception and transduction but would not be able to respond to a signal. C) It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. D) It would employ a transduction pathway directly from an external messenger.
A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
7) Which of the following statements about NAD+ is true? A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. B) NAD+ has more chemical energy than NADH. C) NAD+ can donate electrons for use in oxidative phosphorylation. D) In the absence of NAD+, glycolysis can still function.
A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
6) In which of the following ways do plant hormones differ from hormones in animals? A) Plant hormones most often travel in air as a gas. B) Animal hormones are only local regulators. C) Plant hormones are typically released into the soil. D) Animal hormones are primarily for mating and embryonic development.
A) Plant hormones most often travel in air as a gas.
26) Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction? A) a lipid-soluble signal B) a signal that is weakly bound to a nucleotide C) a signal that binds to a receptor in the cell membrane D) a signal that binds to the ECM
A) a lipid-soluble signal
44) These inside-out membrane vesicles will _____. A) become acidic inside the vesicles when NADH is added B) become alkaline inside the vesicles when NADH is added C) make ATP from ADP and i if transferred to a pH 4 buffered solution after incubation in a pH 7 buffered solution D) hydrolyze ATP to pump protons out of the interior of the vesicle to the exterior
A) become acidic inside the vesicles when NADH is added
44) Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. The second messenger in this pathway is _____. A) cAMP B) G protein C) adenylyl cyclase D) G protein-coupled receptor
A) cAMP
52) Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy? A) glucose B) proteins C) fatty acids D) Such yeast cells will not be capable of catabolizing any food molecules, and therefore, will die.
A) glucose
30) During aerobic respiration, electrons travel downhill in which sequence? A) glucose → NADH → electron transport chain → oxygen B) glucose → pyruvate → ATP → oxygen C) glucose → ATP → electron transport chain → NADH D) food → glycolysis → citric acid cycle → NADH → ATP
A) glucose → NADH → electron transport chain → oxygen
46) Which of the following normally occurs regardless of whether or not oxygen (O2) is present? A) glycolysis B) fermentation C) citric acid cycle D) oxidative phosphorylation (chemiosmosis)
A) glycolysis
47) Which of the following occurs in the cytosol of a eukaryotic cell? A) glycolysis and fermentation B) fermentation and chemiosmosis C) oxidation of pyruvate to acetyl CoA D) citric acid cycle
A) glycolysis and fermentation
29) The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____. A) how ATP is synthesized by a proton motive force B) how electron transport can fuel substrate-level phosphorylation C) the sequence of the electron transport chain molecules D) the reduction of oxygen to water in the final steps of oxidative metabolism
A) how ATP is synthesized by a proton motive force
13) Scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testes. For this to happen there must be direct communication between the extracellular matrix and the developing cells. Which kind of transmembrane protein would most likely be involved in this kind of induction? A) integrins B) collagens C) actins D) fibronectins
A) integrins
28) The electron transport chain _____. A) is a series of redox reactions B) is a series of substitution reactions C) is driven by ATP consumption D) takes place in the cytoplasm of prokaryotic cells
A) is a series of redox reactions
2) Which of the following statements about quorum sensing is FALSE? Quorum sensing _____. A) is cell-cell communication in eukaryotes B) is species specific C) may result in biofilm formation D) is particularly well studied because of its medical importance
A) is cell-cell communication in eukaryotes
11) A G-protein receptor with GTP bound to it _____. A) is in its active state B) signals a protein to maintain its shape and conformation C) will use cGMP as a second messenger D) directly affects gene expression
A) is in its active state
31) The toxin of Vibrio cholerae causes profuse diarrhea because it _____. A) modifies a G protein involved in regulating salt and water secretion B) binds with adenylyl cyclase and triggers the formation of cAMP C) signals IP3 to act as a second messenger for the release of calcium D) modifies calmodulin and activates a cascade of protein kinases
A) modifies a G protein involved in regulating salt and water secretion
32) Which of the following would most likely be an immediate result of a growth factor binding to its receptor? A) protein kinase activity B) adenylyl cyclase activity C) protein phosphatase activity D) phosphorylase activity
A) protein kinase activity
10) Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells? A) Receptor studies indicated that epinephrine was a ligand. B) Glycogen breakdown was observed only when epinephrine was administered to intact cells. C) Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined. D) Epinephrine was known to have different effects on different types of cells.
B) Glycogen breakdown was observed only when epinephrine was administered to intact cells.
51) Why is glycolysis considered to be one of the first metabolic pathways to have evolved? A) It produces much less ATP than does oxidative phosphorylation. B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. C) It is found in prokaryotic cells but not in eukaryotic cells. D) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.
B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
56) Why is apoptosis potentially threatening to the healthy "neighbors" of a dying cell? A) Cell death would usually spread from one cell to the next via paracrine signals. B) Lysosomal enzymes exiting the dying cell would damage surrounding cells. C) Bits of membrane from the dying cell could merge with neighboring cells and bring in foreign receptors. D) Neighboring cells would activate immunological responses.
B) Lysosomal enzymes exiting the dying cell would damage surrounding cells.
18) Which electron carrier(s) function in the citric acid cycle? A) NAD+ only B) NADH and FADH2 C) the electron transport chain D) ADP and ATP
B) NADH and FADH2
23) If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure? A) Oxaloacetate will decrease and citric acid will accumulate. B) Oxaloacetate will accumulate and citric acid will decrease. C) Both oxaloacetate and citric acid will decrease. D) Both oxaloacetate and citric acid will accumulate.
B) Oxaloacetate will accumulate and citric acid will decrease.
53) Why has C. elegans proven to be a useful model for understanding apoptosis? A) The animal does not naturally use apoptosis, but can be induced to do so in the laboratory. B) The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. C) This plant has a long-studied aging mechanism that has made understanding its death just a last stage. D) While the organism ages, its cells die progressively until the whole organism is dead.
B) The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development.
27) What does it mean to say that a signal is transduced? A) The signal enters the cell directly and binds to a receptor inside. B) The physical form of the signal changes from one form to another. C) The signal is amplified, such than even a single molecule evokes a large response. D) The signal triggers a sequence of phosphorylation events inside the cell.
B) The physical form of the signal changes from one form to another.
19) If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production? A) There would be no change in ATP production, but we would observe an increased rate of carbon dioxide production. B) The rates of ATP production and carbon dioxide production would both increase. C) The rate of ATP production would decrease, but the rate of carbon dioxide production would increase. D) Rates of ATP and carbon dioxide production would probably both decrease.
B) The rates of ATP production and carbon dioxide production would both increase.
21) Which of the following is true of steroid receptors? A) The receptor molecules are themselves lipids or glycolipids. B) The receptor may be inside the nucleus of a target cell. C) The unbound steroid receptors are quickly recycled by lysosomes. D) Steroid receptors are typically bound to the external surface of the nuclear membrane.
B) The receptor may be inside the nucleus of a target cell.
12) Testosterone functions inside a cell by _____. A) acting as a signal receptor that activates tyrosine kinases B) binding with a receptor protein that enters the nucleus and activates specific genes C) acting as a steroid signal receptor that activates ion channel proteins D) coordinating a phosphorylation cascade that increases spermatogenesis
B) binding with a receptor protein that enters the nucleus and activates specific genes
15) A drug designed to inhibit the response of cells to testosterone would most likely result in _____. A) lower cytoplasmic levels of cAMP B) a decrease in transcriptional activity of certain genes C) an increase in cytosolic calcium concentration D) a decrease in G protein activity
B) a decrease in transcriptional activity of certain genes
55) If an adult person has a faulty version of the human analog to ced-4 of the nematode, which of the following is most likely to result? A) activation of a developmental pathway found in the worm but not in humans B) a form of cancer in which there is insufficient apoptosis C) formation of molecular pores in the mitochondrial outer membrane D) excess skin loss
B) a form of cancer in which there is insufficient apoptosis
8) The oxygen consumed during cellular respiration is involved directly in which process or event? A) glycolysis B) accepting electrons at the end of the electron transport chain C) the citric acid cycle D) the oxidation of pyruvate to acetyl CoA
B) accepting electrons at the end of the electron transport chain
33) The primary role of oxygen in cellular respiration is to _____. A) yield energy in the form of ATP as it is passed down the respiratory chain B) act as an acceptor for electrons and hydrogen, forming water C) combine with carbon, forming CO2 D) combine with lactate, forming pyruvate
B) act as an acceptor for electrons and hydrogen, forming water
3) In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function? A) formation of mating complexes B) aggregation of bacteria that can cause cavities C) secretion of substances that inhibit foreign bacteria D) digestion of unwanted parasite populations
B) aggregation of bacteria that can cause cavities
54) High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of _____. A) competitive inhibition B) allosteric regulation C) the specificity of enzymes for their substrates D) positive feedback regulation
B) allosteric regulation
39) The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of _____. A) active transport B) an endergonic reaction coupled to an exergonic reaction C) a reaction with a positive ΔG D) allosteric regulation
B) an endergonic reaction coupled to an exergonic reaction
34) Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of _____. A) phosphorylated proteins B) cAMP C) adenylyl cyclase D) activated G proteins
B) cAMP
22) Particular receptor tyrosine kinases (RTKs) that promote excessive cell division are found at high levels on various cancer cells. A protein, Herceptin, has been found to bind to an RTK known as HER2. HER2 is sometimes excessive in cancer cells. This information can now be utilized in breast cancer treatment if which of the following is true? A) if HER2, administered by injection, causes cell division B) if the patient's cancer cells have excessive levels of HER2 C) if the patient's genome codes for the HER2 receptor D) if the patient has RTKs only in cancer cells
B) if the patient's cancer cells have excessive levels of HER2
19) Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because _____. A) only target cells retain the appropriate DNA segments B) intracellular receptors are present only in target cells C) only target cells possess the cytosolic enzymes that transduce the testosterone D) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor
B) intracellular receptors are present only in target cells
50) Scaffolding proteins are _____. A) microtubular protein arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores B) large molecules to which several relay proteins attach to facilitate cascade effects C) relay proteins that orient receptors and their ligands in appropriate directions to facilitate their complexing D) proteins that can reach into the nucleus of a cell to affect transcription
B) large molecules to which several relay proteins attach to facilitate cascade effects
2) The molecule that functions as the reducing agent (electron donor) in a redox or oxidation- reduction reaction _____. A) gains electrons and gains potential energy B) loses electrons and loses potential energy C) gains electrons and loses potential energy D) loses electrons and gains potential energy
B) loses electrons and loses potential energy
55) Glycolysis is active when cellular energy levels are _____; the regulatory enzyme, phosphofructokinase, is _____ by ATP. A) low; activated B) low; inhibited C) high; activated D) high; inhibited
B) low; inhibited
31) Where are the proteins of the electron transport chain located? A) mitochondrial outer membrane B) mitochondrial inner membrane C) mitochondrial intermembrane space D) mitochondrial matrix
B) mitochondrial inner membrane
20) Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? A) glycolysis and the oxidation of pyruvate to acetyl CoA B) oxidation of pyruvate to acetyl CoA and the citric acid cycle C) oxidative phosphorylation and fermentation D) fermentation and glycolysis
B) oxidation of pyruvate to acetyl CoA and the citric acid cycle
5) When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____. A) hydrolyzed B) oxidized C) reduced D) an oxidizing agent
B) oxidized
14) In glycolysis, for each molecule of glucose oxidized to pyruvate _____. A) two molecules of ATP are used and two molecules of ATP are produced. B) two molecules of ATP are used and four molecules of ATP are produced. C) four molecules of ATP are used and two molecules of ATP are produced. D) two molecules of ATP are used and six molecules of ATP are produced.
B) two molecules of ATP are used and four molecules of ATP are produced.
40) If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? A) 0 B) 12 C) 14 D) 26
C) 14
21) If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle? A) 1/6 B) 1/3 C) 2/3 D) all of it
C) 2/3
24) Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the accompanying figure)? A) 1 ATP, 2 CO2, 3 NADH, and 1 FADH2 B) 3 ATP, 3 CO2, 3 NADH, and 3 FADH2 C) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2 D) 38 ATP, 6 CO2, 3 NADH, and 12 FADH2
C) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2
47) Put the steps of the process of signal transduction in the order they occur: 1. A conformational change in the signal-receptor complex activates an enzyme. 2. Protein kinases are activated. 3. A signal molecule binds to a receptor. 4. Target proteins are phosphorylated. 5. Second messenger molecules are released. A) 1, 2, 3, 4, 5 B) 3, 1, 2, 4, 5 C) 3, 1, 5, 2, 4 D) 1, 2, 5, 3, 4
C) 3, 1, 5, 2, 4
61) Which of the following poses the best evidence that cell-signaling pathways evolved early in the history of life? A) Cell-signaling pathways are seen in "primitive" cells such as bacteria and yeast. B) Bacteria and yeast cells signal each other in a process called quorum sensing. C) Signal transduction molecules identified in distantly related organisms are similar. D) Most signals in all types of cells are received by cell surface receptors.
C) Signal transduction molecules identified in distantly related organisms are similar.
62) Cells that are infected, damaged, or have reached the end of their functional life span often undergo "programmed cell death." This controlled cell suicide is called apoptosis. Select the appropriate description of this event on a cell's life cycle. A) Apoptosis is regulated by cell surface receptors that signal when a cell has reached its density-dependent limits. B) During apoptosis, dying cells leak out their contents including digestive enzymes that also destroy healthy cells. C) During apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell. D) Each cell organelle has protein signals that initiate the breakdown of the organelle's components which leads to cell death.
C) During apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell.
37) Which of the following is a correct association? A) kinase activity and the addition of a tyrosine B) phosphodiesterase activity and the removal of phosphate groups C) GTPase activity and hydrolysis of GTP to GDP D) adenylyl cyclase activity and the conversion of cAMP to AMP
C) GTPase activity and hydrolysis of GTP to GDP
41) In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A) It allows for an increased rate of glycolysis. B) It allows for an increased rate of the citric acid cycle. C) It increases the surface for oxidative phosphorylation. D) It increases the surface for substrate-level phosphorylation.
C) It increases the surface for oxidative phosphorylation.
12) The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed? A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis. B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat. C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. D) There is no CO2 or water produced as products of glycolysis.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
54) Which of the following describes the events of apoptosis? A) The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. B) The cell's DNA and organelles become fragmented, the cell dies, and it is phagocytized. C) The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells. D) The cell's nucleus and organelles are lysed, then the cell enlarges and bursts.
C) The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells.
26) Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate? A) glyceraldehyde 3-phosphate B) oxaloacetate C) acetyl CoA D) citrate
C) acetyl CoA
38) Protein kinase is an enzyme that _____. A) functions as a second messenger molecule B) serves as a receptor for various signal molecules C) activates or inactivates other proteins by adding a phosphate group to them D) produces second messenger molecules
C) activates or inactivates other proteins by adding a phosphate group to them
28) Protein phosphorylation is commonly involved with all of the following EXCEPT _____. A) regulation of transcription by extracellular signaling molecules B) enzyme activation C) activation of G protein-coupled receptors D) activation of protein kinase molecules
C) activation of G protein-coupled receptors
58) Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in _____. A) photosynthetic cells in the light, while photosynthesis occurs concurrently B) cells that are storing glucose only C) all cells all the time D) photosynthesizing cells in the light and in other tissues in the dark
C) all cells all the time
51) Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they _____. A) are species specific B) always lead to the same cellular response C) amplify the original signal many times D) counter the harmful effects of phosphatases
C) amplify the original signal many times
15) Which kind of metabolic poison would most directly interfere with glycolysis? A) an agent that reacts with oxygen and depletes its concentration in the cell B) an agent that binds to pyruvate and inactivates it C) an agent that closely mimics the structure of glucose but is not metabolized D) an agent that reacts with NADH and oxidizes it to NAD+
C) an agent that closely mimics the structure of glucose but is not metabolized
56) Canine phosphofructokinase (PFK) deficiency afflicts Springer spaniels, affecting an estimated 10% of the breed. Given its critical role in glycolysis, one implication of the genetic defect resulting in PFK deficiency in dogs is _____. A) early embryonic mortality B) elevated blood-glucose levels in the dog's blood C) an intolerance for exercise D) a reduced life span
C) an intolerance for exercise
1) In yeast signal transduction, a yeast cell releases a mating factor which _____. A) acts back on the same cell that secreted the mating factor, changing its development B) passes through the membranes of neighboring cells, binds to DNA, and initiates transcription C) binds to receptors on the membranes of other types of yeast cells D) diffuses through the membranes of distant cells, causing them to produce factors that initiate long-distance migrations
C) binds to receptors on the membranes of other types of yeast cells
48) Transcription factors _____. A) regulate the synthesis of DNA in response to a signal B) transcribe ATP into cAMP C) control gene expression D) regulate the synthesis of lipids in the cytoplasm
C) control gene expression
37) When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____. A) formation of ATP B) reduction of NAD+ C) creation of a proton-motive force D) lowering of pH in the mitochondrial matrix
C) creation of a proton-motive force
35) In chemiosmosis, what is the most direct source of energy that is used to convert ADP + to ATP? A) energy released as electrons flow through the electron transport system B) energy released from substrate-level phosphorylation C) energy released from movement of protons through ATP synthase, down their electrochemical gradient D) No external source of energy is required because the reaction is exergonic.
C) energy released from movement of protons through ATP synthase, down their electrochemical gradient
9) Carbohydrates and fats are considered high-energy foods because they _____. A) have a lot of oxygen atoms. B) have no nitrogen in their makeup. C) have a lot of electrons associated with hydrogen. D) are easily reduced.
C) have a lot of electrons associated with hydrogen
52) GTPase activity is important in the regulation of signal transduction because it _____. A) increases the available concentration of phosphate B) decreases the amount of G protein in the membrane C) hydrolyzes GTP to GDP, thus shutting down the pathway D) converts cGMP to GTP
C) hydrolyzes GTP to GDP, thus shutting down the pathway
1) Substrate-level phosphorylation occurs _____. A) in glycolysis B) in the citric acid cycle C) in both glycolysis and the citric acid cycle D) during oxidative phosphorylation
C) in both glycolysis and the citric acid cycle
30) Which of the following is the best explanation for the inability of a specific animal cell to reduce the Ca2+ concentration in its cytosol compared with the extracellular fluid? A) blockage of the synaptic signal B) loss of transcription factors C) insufficient ATP levels in the cytosol D) low levels of protein kinase in the cell
C) insufficient ATP levels in the cytosol
24) Which of the following is characteristic of a steroid hormone action? A) protein phosphorylation B) cell-surface receptor binding C) internal receptor binding D) second messenger activation
C) internal receptor binding
18) Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane? A) receptor tyrosine kinase B) G protein-coupled receptor C) ligand-gated ion channel D) intracellular receptor
C) ligand-gated ion channel
59) Apoptosis involves all but which of the following? A) fragmentation of the DNA B) activation of cellular enzymes C) lysis of the cell D) digestion of cellular contents by scavenger cells
C) lysis of the cell
36) Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells? A) mitochondrial outer membrane B) mitochondrial inner membrane C) mitochondrial intermembrane space D) mitochondrial matrix
C) mitochondrial intermembrane space
34) During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from? A) carbon dioxide (CO2) B) glucose (C6H12O6) C) molecular oxygen (O2) D) pyruvate (C3H3O3-)
C) molecular oxygen (O2)
49) One function of both alcohol fermentation and lactic acid fermentation is to _____. A) reduce NAD+ to NADH B) reduce FAD+ to FADH2 C) oxidize NADH to NAD+ D) reduce FADH2 to FAD+
C) oxidize NADH to NAD+
4) Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells? A) hormonal signaling B) autocrine signaling C) paracrine signaling D) synaptic signaling
C) paracrine signaling
33) Adenylyl cyclase has the opposite effect of which of the following? A) protein kinase B) protein phosphatase C) phosphodiesterase D) phosphorylase
C) phosphodiesterase
35) An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum? A) serine/threonine kinases B) phosphodiesterase C) phospholipase C D) adenylyl cyclase
C) phospholipase C
6) When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes _____. A) dehydrogenated B) oxidized C) reduced D) redoxed
C) reduced
40) Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction? A) tyrosines B) glycine and histidine C) serine and threonine D) glycine and glutamic acid
C) serine and threonine
7) When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway? A) relay molecule B) transducer C) signal molecule D) response molecule
C) signal molecule
25) The receptors for steroid hormones are located inside the cell instead of on the membrane surface like most other signal receptors. This is not a problem for steroids because _____. A) the receptors can be readily stimulated to exit and relocate on the membrane surface B) steroids do not directly affect cells but instead alter the chemistry of blood plasma C) steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane D) steroids must first bond to a steroid activator, forming a complex that then binds to the cell surface
C) steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane
27) Which of the following events takes place in the electron transport chain? A) the breakdown of glucose into two pyruvate molecules B) the breakdown of an acetyl group to carbon dioxide C) the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle D) substrate-level phosphorylation
C) the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle
42) If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound _____. A) that activates epinephrine receptors B) that increases cAMP production in liver cells C) to block G protein activity in liver cells D) that increases phosphorylase activity
C) to block G protein activity in liver cells
11) Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis? A) 0% B) 2% C) 38% D) 100%
D) 100%
38) Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration? A) 2 B) 4 C) 18-24 D) 30-32
D) 30-32
46) Which of the following is true during a typical cAMP-type signal transduction event? A) The second messenger is the last part of the system to be activated. B) The hormone activates the second messenger by directly binding to it. C) The second messenger amplifies the hormonal response by attracting more hormones to the cell being affected. D) Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.
D) Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.
49) At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects? A) Estrogen is produced in very large concentration by nearly every tissue of the body. B) Each cell responds in the same way when steroids bind to the cell surface. C) Estrogen is kept away from the surface of any cells not able to bind it at the surface. D) Estrogen binds to specific receptors inside many kinds of cells, each with different responses.
D) Estrogen binds to specific receptors inside many kinds of cells, each with different responses.
32) During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level? A) NADH B) ATP C) ADP + Pi D) FADH2
D) FADH2
17) Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____. A) acetyl-CoA B) glucose C) pyruvate D) NADH
D) NADH
36) Which of the following statements is true of signal molecules? A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. B) In response to some G protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP3 and calcium. C) In most cases, signal molecules interact with the cell at the plasma membrane, enter the cell, and eventually enter the nucleus. D) Protein kinase A activation is one possible result of signal molecules binding to G protein- coupled receptors.
D) Protein kinase A activation is one possible result of signal molecules binding to G protein- coupled receptors.
45) Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _____. A) all cells, but only in the presence of oxygen B) only eukaryotic cells, in the presence of oxygen C) only in mitochondria, using either oxygen or other electron acceptors D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
59) In respiration, beta oxidation involves the _____. A) oxidation of glucose B) oxidation of pyruvate C) regulation of glycolysis D) breakdown of fatty acids
D) breakdown of fatty acids
60) Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groups of acetyl CoA molecules. These acetyl groups _____. A) directly enter the electron transport chain B) directly enter the energy-yielding stages of glycolysis C) are directly decarboxylated by pyruvate dehydrogenase D) directly enter the citric acid cycle
D) directly enter the citric acid cycle
45) Sutherland discovered that the signaling molecule epinephrine _____. A) brings about a decrease in levels of cAMP as a result of bypassing the plasma membrane B) causes lower blood glucose by binding to liver cells C) interacts directly with glycogen phosphorylase D) elevates cytosolic concentrations of cyclic AMP
D) elevates cytosolic concentrations of cyclic AMP
5) Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must _____. A) modify its plasma membrane to alter the hormone entering the cytoplasm B) be from the same cell type as the organ that produced the hormone C) experience an imbalance that disrupts its normal function D) have receptors that recognize and bind the hormone molecule
D) have receptors that recognize and bind the hormone molecule
41) In signal transduction, phosphatases _____. A) move the phosphate group of the transduction pathway to the next molecule of a series B) prevent a protein kinase from being reused when there is another extracellular signal C) amplify the second messengers such as cAMP D) inactivate protein kinases and turn off the signal transduction
D) inactivate protein kinases and turn off the signal transduction
50) An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism _____. A) is a normal eukaryotic organism B) is photosynthetic C) is an anaerobic organism D) is a facultative anaerobe
D) is a facultative anaerobe
53) What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+ A) NADH B) NAD+ C) lactate D) pyruvate
D) pyruvate
23) Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins? A) G protein-coupled receptor binding B) ligand-gated ion channel signaling C) adenylyl cyclase activity D) receptor tyrosine kinase activity
D) receptor tyrosine kinase activity
14) One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this? A) G protein-coupled receptors B) ligand-gated ion channels C) steroid receptors D) receptor tyrosine kinases
D) receptor tyrosine kinases
43) If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound _____. A) that mimics epinephrine and can bind to the epinephrine receptor B) that stimulates cAMP production in liver cells C) to stimulate G protein activity in liver cells D) that increases phosphodiesterase activity
D) that increases phosphodiesterase activity
16) Most of the CO2 from the catabolism of glucose is released during _____. A) glycolysis B) electron transport C) chemiosmosis D) the citric acid cycle
D) the citric acid cycle
